In automobiles and other vehicles, antenna systems are necessary for reception of radio waves and also television broadcast signals. A traditional monopole type antenna has served this function and is one of the conventional antenna systems available. The monopole antenna projects outward of the exterior of the vehicle and exhibits satisfactory performance in the reception of radio waves. However, the monopole and other externally projecting antennas are obstructions in the design of vehicle bodies, are easily damaged, and are a source of unwanted wind noise.
Moreover, a modern trend in the field automobiles is to include a variety of receivers and transmitters, each of which has its own antenna. For example, a modern vehicle may have an antenna for broadcast radio, another antenna for a cellular radio telephone or a 2-way radio, and yet another antenna for television reception. Unfortunately, the addition of more externally projecting antennas exacerbates the problems of externally projecting antennas on vehicles.
Some attempts have been made to improve on the externally projecting antennas by embedding antennas in windshields, relying upon electrical currents induced on the vehicle body, and the like. Unfortunately, attenuation of radio signals by the vehicle body has led to undesirably poor reception. In addition, such conventional approaches have been susceptible to electrical noise which is generated by the motor and other components of the vehicle. Furthermore, such systems tend to require an excessive number of components and complex manufacturing processes, each of which raises costs to undesirably high levels.